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Going About Bicycling & Carbon Footprinting Wrongly

August 10, 2011

Why are we even having this conversation? This ludicrous system of calculation was recently posted on Slate. Basically, the story tries to determine how many miles of riding would be required to eliminate the carbon footprint associated with buying a new bike. The piece starts:

I’m thinking about switching my daily commute from four wheels to two. But I’m concerned about all the energy it takes to manufacture and ship a new bicycle. How many miles would I need to substitute a bike for my car before I’ve gone “carbon neutral”?

While it’s nice to applaud this level of concern, the following formulae seem somewhat skewed in ways that seem to utterly miss the point.

It’s tough to say exactly how much greenhouse gas making a bicycle requires, since none of the major manufacturers has released data on their energy consumption. Independent analysts have used a couple of different measures. Shreya Dave, a graduate student at MIT, recently estimated that manufacturing an average bicycle results in the emission of approximately 530 pounds of greenhouse gases (PDF). Umbra Fisk, a research associate at Grist, came up with a total carbon footprint of one ton of carbon dioxide-equivalents for every $1,000 of manufacturing cost. These two estimates intersect at a bike that costs $265 to build—well within the range of manufacturing costs for the wide variety of bicycles on the market.

So that’s the goal: To trim about 530 pounds of CO2 emissions from your commute. There’s been a lot of hemming and hawing about how biking or walking might not be so eco-friendly because your body burns more calories during those activities than while driving. But, frankly, that’s bunk: As the Pacific Institute has shown, you’d have to be eating an all-beef diet to offset the environmental benefits of walking or bicycling. Given a “typical U.S. diet,” you would have to ride your bike instead of driving for around 400 miles to cover the bike’s initial carbon footprint.

The geek in me likes all the numbers being thrown around, but the humanities professor in me thinks this is all missing the point, or failing to take in a number of critical variables. For starters, rather than separating machine and operator, why not link calorie consumption to fuel consumption since both are making the vehicle move forward. But there are bigger aspects of this investigation that deserve greater attention. Frankly, the majority of North Americans commute between home and work at such a distance that cycling is fairly impractical. The conversion to bicycling might imply living at greater proximity to place of work, which would cut down on the size of any carbon footprint. Moreover, living closer to an urban centre typically means living in a smaller home. Single-family houses in new, suburban estates are massive compared with houses built even fifty years ago, during the first raft of large-scale suburban construction. And the closer you move to a city centre, the more dense the population. All of these things contribute to reducing carbon footprints in myriad ways.

So, lifestyle choices factor in in ways that warrant consideration. More condensed neighborhoods also tend to build community more effectively. Maybe it’s the trees or the proximity to communal shops (or distance from chain box stores). And the bicycle allows for greater opportunity for chance encounters in such communities. But these kinds of numbers and possibilities don’t register in the equations trying to determine whether a new bicycle is a good idea. On a stand-alone basis, this kind of sterile calculation is next to meaningless.

Also, this. Urban centres in North America remain decidedly unfriendly to bicycle traffic. These “rules” for urban cycling were recently posted on Velominati. Terrific—and wise—stuff. Car-light living requires substantial—almost revolutionary—changes. They do, however, seem to want to promote healthier living on an individual basis and greener living on a collective one.

Another interesting bike commuting link:

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